Managing Energy Costs in Ice Rinks

Ice rinks are highly energy-intensive businesses that can benefit from energy-saving strategies. Implementing measures that save energy can boost your bottom line and help your ice rink develop a greener image. The measures described below are generally among the most effective options, yielding substantial energy savings with short simple payback periods.

Most electricity consumption in ice rinks generally goes toward refrigeration, lighting, pumps, and fans, and most thermal energy goes toward heating (Figure 1). Because these facilities require simultaneous heating and cooling, efficiency measures that can reduce one load individually will affect the energy consumption of the other, as well. For example, a reduction in air temperature, which lowers the amount of energy required for space heating, will also cause the ice to melt more slowly, thereby reducing the refrigeration load.

Average energy use data

Figure 1: Average energy use in a Canadian ice rink

Heating generally represents one of the largest sources of energy consumption in ice rinks, and it can be drastically reduced through a variety of measures. End-use energy consumption is shown for a typical inefficient ice rink (A) as well as a highly efficient ice rink using heat recovery and other energy-saving measures (B).

Because the refrigeration and pumping systems in ice plants comprise the majority of electricity consumption in ice rinks, they are great areas for applying efficiency measures. Figure 2 shows typical heat sources in a standard ice rink. The best areas for refrigeration savings are generally found through reducing radiated heat, rink temperature and humidity, brine pump work (used for chilling the ice), and ice resurfacing.

Figure 2: Refrigeration system heat sources

Energy-saving measures should be targeted at the areas that have large loads on the refrigeration system. Reducing impacts from radiant heat, humidity, rink temperature, brine pump work, and ice resurfacing will yield the best results.

Quick Fixes

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Many ice rinks can realize substantial savings quickly and easily by making basic changes to existing equipment. Changes to equipment operations frequently offer the largest potential to save energy, followed by changes to maintenance procedures.

Heating

Heating systems can represent the largest single source of energy consumption in ice rinks, so they are also one of the areas with the greatest potential for energy reductions.

Adjust air temperature. In many ice rinks, air temperature is set to between 55° and 60° Fahrenheit (F) to ensure that spectators are comfortable. However, because air temperature affects the amount of energy used by both the HVAC system and the ice plant (because the ice will melt faster at higher ambient temperatures), something as simple as turning down the heat when few spectators are present can have a drastic effect on energy use. In Canada, ice rinks that have reduced air temperature from 60°F to about 40°F have realized overall energy savings of 25 to 50 percent.

Melt ice outside the facility. Instead of melting ice inside, take it outside to melt; this process can reduce heating loads and save substantial amounts of energy. Furthermore, recovered heat from condensers can be applied to melt the ice faster. Check environmental regulations about paint and other potentially hazardous materials as they relate to disposing of ice shavings outside.

Lighting

Improving the efficiency of your lighting systems can be straightforward and inexpensive, and it’s an easy way to save energy.

Change light intensity. Consider adapting the level of lighting to the activity taking place. Although some events, such as hockey games, may require high-intensity lighting, many activities will be unaffected by reduced light levels. You will save electricity by shrinking your lighting load and also help to reduce the cooling load for the ice rink.

Install occupancy sensors. Areas that are not consistently occupied—such as storage rooms, restrooms, back offices, and hallways—are ideal places for occupancy sensors. By automatically turning off lights in unoccupied areas, these sensors can save 30 to 75 percent of lighting-energy consumption and typically yield simple payback periods of one to three years.

Other Measures

Install time clocks. Time clocks connected to equipment will ensure that they are shut off at appropriate times. These clocks can be much more effective than manual switches because there is no need for someone to remember to manually shut systems off. Time clocks are a great choice if you plan to shut down the refrigeration plant at night, although override controls should be installed for critical functions to ensure that no problems arise.

Shut down the refrigeration plant at night. Shutting down the refrigeration plant at night can be a highly effective operational procedure if done correctly. The brine pump should also be turned off, and space heating should be set back to 35°F. A slab sensor should be used to turn the brine pump and a single compressor back on once the slab reaches 25°F, to prevent further warming. It’s important to note that a slab sensor is necessary, and a brine return sensor will not work while the pump is off. In the morning, it will be easy to cut and groom the soft ice, increasing ice maintenance equipment lifespans and saving on fuel costs.

While the compressor recools the ice in the morning, be sure to keep lights and unnecessary equipment off to avoid increasing demand. Shutting down refrigeration at night will save energy, but if a new peak demand is reached the following morning when unnecessary equipment turns on, energy savings may be overshadowed by increased demand charges on the resulting energy bill.

Optimize ice thickness. Although the layer of ice in the rink needs to be thick enough to support skaters, the refrigeration equipment will work harder than necessary if ice is unnecessarily thick, resulting in wasted energy. Check the thickness of the ice sheet to ensure that it’s between 1.0 and 1.5 inches.

Longer-Term Solutions

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Though operational measures and equipment maintenance are low-hanging fruit, greater investments in retrofits and equipment upgrades can provide large persistent savings with potentially short payback periods.

Install LED lighting. LEDs offer several advantages over conventional light sources, including high efficiency, long life, and superior control. These characteristics, along with falling prices, have made LEDs a viable solution for a growing number of applications.

In particular, LED troffers offer a number of benefits in the right applications, and prices continue to fall. Troffers are long, recessed lighting fixtures that are typically installed with the opening flush with the ceiling and with their inner surface serving as a reflector. The best LED troffer products currently outperform their fluorescent cousins, and replacement options include new LED troffers, LED retrofit kits, or fluorescent tubes swapped for tubular LED products.

For more information on choosing LEDs, see the section “How To Make The Best Choice” located on our LED page.

Add heat recovery. On average, as much as 7.2 million Btu of heat, or more than 2,000 kilowatt-hours, are generated each day by an ice plant—more than enough to satisfy the entire daily heating load of the ice rink while having excess thermal energy available for other purposes. By implementing heat-recovery systems, ice rinks can realize overall heating savings of more than 75 percent. Most of the waste heat available comes from the refrigeration condenser, but some heat can be also recovered from the building’s exhaust air. Recovered heat can be used for space heating, domestic water heating, subfloor heating, floodwater heating, ice melting, and preheating cold outdoor air for ventilation.

Add pressure controls. Many refrigeration systems are designed for outdoor temperatures of 86°F and, as a result, often have higher head pressures than needed, resulting in high condensing temperatures and increased electrical consumption. Particularly in cold climates, modulating head pressure based on outdoor air temperature can yield refrigeration savings as high as 25 percent.

Install adjustable-speed drives.Adjustable-speed drives match a machine’s motor output to its real-time load. They can be an effective way to save energy in condenser and brine pumps. By reducing pump speed when possible, ASDs can reduce not only the energy consumption of the pumps themselves, but also the amount of heat added to the brine through friction (which increases cooling loads).

Optimize brine use. Brine should be kept at a specific gravity of 1.20 to 1.22 for most efficient energy use. To measure the specific gravity, or density relative to water, use a hydrometer. Make sure to let the brine sample warm up to 60°F before testing. Specific gravity is measured relative to water, which has a specific gravity of 1.0. To adjust the specific gravity, add calcium chloride flakes to increase (mix in a barrel and add through mixing valve), or dilute the brine with water to decrease. Insulating the brine storage tank will reduce cooling losses and heating costs in the compressor room.

Use the brine line as a dehumidifier. Using a return brine loop in the corner of the ice rink can be a great trick to keep humidity—and thus refrigeration loads—under control. Set the brine to 22°F, which will cause frost to form on the line, removing water from the air. A defrost cycle is required to melt the frost and drain the melt water into a drain pit. This will help to keep humidity levels under 50 percent and prevent cooling loads from increasing significantly. An alternative is to use a refrigeration dehumidifier, which extracts moisture by cooling the air on coils.

Use ceiling modifications that radiate less heat. Nearly 30 percent of the total refrigeration load in heated rinks is radiated from the arena ceiling. After reflective paint or ceiling curtains are installed, making the ceiling less emissive, ice rinks may demonstrate energy savings of up to 80 percent of the radiated heat (equivalent to around 24 percent of total refrigeration load), particularly when they are located in warm, humid climates. Low-emissivity ceilings can also help to boost illumination levels and reduce ceiling condensation.

Implement a building automation system. Installing a computerized building automation system (BAS) is an expensive commitment with substantial up-front costs, but it can provide many benefits. Considering the costs of a BAS, a thorough economic analysis should be performed before the system is installed. Using a BAS can be a particularly good option for large facilities with high energy consumption. Facility management should explore additional applications that the system may be able to automate to help substantiate its feasibility. For example, many systems can also handle registrations, inventory, and accounting. In ice rinks, a computerized BAS can control:

Refrigeration systems

Brine pumps

Ice temperature

Lighting and illumination levels

Ventilation equipment

Heating systems

Other electric equipment

Domestic water heating

Demand functions

Some of the main energy-saving functions available include:

On/off switching

Dimming and setback

Thermostat adjustments

Time of day scheduling

Demand control

Equipment monitoring

Alarm functions

De-gas resurfacing water. According to ASHRAE, domestic hot water and resurfacing generally accounts for 7 percent of an ice rink’s total energy use. The more impurities water contains (both minerals and dissolved gas), the colder it needs to be before it will freeze. More energy is required to do lower that temperature, and the resulting ice will have poorer quality. To address these issues, most ice rinks boil water to remove dissolved gas before resurfacing the rink. However, this technique not only requires energy to heat the water but also increases the refrigeration load because warm water is being applied directly to the ice.

Instead of boiling resurfacing water, a new approach called vortex water treatment can remove air bubbles passively: It creates a vortex in the water line that isolates bubbles in a low-pressure zone, removing them from the water. This results in harder, smoother ice that requires less maintenance. Vortex-treated water has fewer impurities than boiled water and can therefore be frozen at a higher temperature. The process saves energy in several ways: Natural gas is saved by eliminating the need to heat resurfacing water. Electricity is saved by directly reducing the refrigeration load and through raising the ice slab temperature.

Consider synthetic ice. When planning new construction or major retrofits, consider installing synthetic ice. Synthetic ice is a solid polymer material designed for skating using normal metal-bladed skates. Synthetic ice will wear down the skates faster and must be cleaned regularly to maintain rink attractiveness. Although you’ll need to evaluate the performance of the synthetic ice product with respect to your facility’s needs, this measure can effectively eliminate almost all major sources of energy consumption in ice rinks.